New observations of the planets orbiting around the Trappist-1 star, described it as a "holy grail" discovery – which caused a stir when scientists found a whole set of Earth-like worlds circling it last year – show more detailed information than ever about what life could be like on those planets. The seven planets are made mostly of rock, like the Earth. About 5 per cent of their mass is made up of water – far more wet than Earth, which is only 0.02 per cent water.
Water is the key thing scientists look for on potential "second Earths", and all agree that water, ideally in its liquid state, is a prerequisite for life as we know it.
At least four of the Trappist-1 planets are thought to have temperate climates, opening up the possibility of surface oceans, lakes or rivers. One, Trappist-1e, stands out as being the most Earth-like in terms of its size, density and the amount of light energy received from its star.
"Of the seven planets, and of all the exoplanets that have been identified so far, Trappist-1e most resembles Earth, when we consider the amount of energy a planet receives from its star, and its density, which reflects its internal composition," said Amaury Triaud, from the University of Birmingham, a leading member of the international discovery team. "Our next step is to find out whether the planet has an atmosphere, since our only method to detect the presence of biology beyond the solar system relies on studying the chemistry of an exoplanet's atmosphere."
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